1. Field of the Invention
The present invention relates to a method for producing an intermetallic compound. In particular, the present invention relates to a method for producing an intermetallic compound having a desired composition by melting an intermetallic compound by means of an electron beam.
2. Description of the Related Art
Those hitherto known as methods for producing intermetallic compounds such as those based on a Nb--Al system include a powder metallurgy method and a pressurized atmosphere melting method for melting a material while adjusting a pressurized condition of a rare gas such as Ar. These methods are designed to obtain an intermetallic compound containing components in a desired stoichiometric ratio by controlling the amount of evaporation of a readily volatile metal which is relatively easy to evaporate, such as Al.
Japanese Patent Publication No. 7-17970 discloses a plasma electron beam melting and casting method for Al-containing intermetallic compounds, in which a compressed preparation of a material of an intermetallic compound is melted in a water-cooled horizontal copper mold to obtain a rod-shaped ingot, and the ingot is melted by irradiating it with a plasma electron beam to perform solidification while dripping the melted metal. In this method, evaporation of Al is controlled by finely adjusting the flow amount of an inert gas to be introduced when the ingot is irradiated with the plasma electron beam.
However, in the case of the powder metallurgy method, the grain boundary tends to become brittle due to intergranular oxidation, and an obtained intermetallic compound is insufficient in processability. If a third component is added in order to improve the processability, characteristics originally possessed by the intermetallic compound may be deteriorated. On the other hand, the pressurized atmosphere melting method is excellent in adjustment of the stoichiometric ratio, however, it is impossible to expect any purification effect for removing impurity gas elements by means of volatilization. In the conventional methods as described above, mechanical and physical characteristics inherent in a material itself are not embodied due to the occurrence of fracture in the grain boundary itself and the influence exerted by contained impurities, in addition to the characteristic fracture mechanism based on the cleavage property inherent in the intermetallic compound.